1. Field of the Invention
The present invention relates to medical devices, and more particularly, to airway products, such as tracheal tubes and cuffs.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the course of treating a patient, a tube or other medical device may be used to control the flow of air, food, fluids, or other substances into and/or out of the patient. For example, medical devices such as tracheal tubes may be used to control the flow of one or more substances into or out of a patient. In many instances it is desirable to provide a seal between the outside of the tube or device and the interior of the passage in which the tube or device is inserted. In this way, substances can only flow through the passage via the tube or other medical device, allowing a medical practitioner to maintain control over the type and amount of substances flowing into and out of the patient.
For example, tracheal tubes may be used to control the flow of air or other gases through a patient's trachea. Such tracheal tubes may include endotracheal (ET) tubes or tracheostomy tubes. To seal these types of tracheal tubes, an inflatable cuff may be associated with these tubes. When inflated, the cuff generally expands into the surrounding trachea to seal the tracheal passage around the tube.
However, to fit a range of trachea anatomies and to provide low intra cuff pressure, cuff diameters are typically about one and a half times the diameter of the average trachea. Therefore, when inserted in an average-sized trachea, such a cuff is unable to fully expand and will fold in on itself within the trachea. These folds may serve as leak paths that allow mucosal secretions to flow past the cuff and enter the lung. Because mucosal secretions may harbor microbes, it is desirable to prevent such secretions from entering the lungs.
Certain types of cuffs are manufactured from materials that have a lower tendency to form leak paths. For example, high pressure cuffs are typically made of highly elastic materials that may form a relatively smooth seal against the trachea. However, such cuffs have associated disadvantages. Due to their elastic properties, high pressure cuffs are often inflated to at least twice the intracuff pressure of lower pressure cuffs in order to form a sufficient tracheal seal. Such high pressures may cause patient discomfort. Further, the mechanical pressure of the high pressure cuff against the tracheal walls may also cause temporary damage to cilial structures in the trachea that are associated with airway particle clearance.
Other types of cuffs may include swellable layers that may be involved in providing a physical barrier to fill the leak paths. However, such physical barriers may be nonetheless permeable to microbial infiltration. For example, such cuffs may employ a hydrogel that may swell into the folds of the cuff. However, many hydrogel coatings may be too porous to prevent the microbes in mucosal secretions from flowing through leak paths in the cuff. Further, many hydrogel coatings are dynamic in nature, with constantly changing pore sizes.